--- id: uefn-epic-update-troubleshooting title: Fortnite and UEFN update will not install tags: - launcher - update - install - verify - fortnite - uefn when_to_use: Before diagnosing a Fortnite or UEFN update that will not install on Windows. Call get_skill('uefn-epic-update-troubleshooting') first. Covers a false still-running lock, install-helper verify failures, and a follower UEFN update blocked because Fortnite is Pending. Verify is the repair. Do not edit files inside the game install. --- # Fortnite and UEFN update will not install Call this skill **before** diagnosing a Fortnite or Unreal Editor for Fortnite update that will not install on Windows. This page is the hosted playbook. Do not invent a second one. It tells you what the failure is, which signature you are on, and which existing tool or Epic control does the next step. It does not install the game for you. LOOKUP ORDER: 1. `get_skill('uefn-epic-update-troubleshooting')` (this page). 2. Read-only snapshot: client script `scripts/Get-EpicUpdateState.ps1` (uefn-mcp). If local `tools/list` has a tool that runs that script, call the tool. Do not write a second snapshot. 3. Epic Games Launcher **Verify** (Library, three dots, Manage, Verify) for the app the snapshot names. There is no hosted tool that clicks Verify. 4. `search_verse_kb` `mode=docs` for the Epic help page that matches the code on screen. `mode=howto` for the public guide `fortnite-uefn-update-will-not-install`. A stale **MCP client** is not this job. That one-liner is `get_skill('uefn-welcome')`. Depot sync is `get_skill('uefn-p4')`. Editor bind and inspect is `get_skill('epic-valkyrie-mcp')`. ## What this covers, and what it does not Use it when the Epic Games Launcher will not finish an update or install of Fortnite or UEFN on Windows: the button says the app is still running, an install error code is on the tile, the update retries and quits, or UEFN sits queued while Fortnite never leaves an interrupted update. Do not use it for Mac, console, mobile, or cloud play. Do not use it for sign-in, two-factor, payment, or bans. Do not use it for Verse compile errors, devices, or project content. Do not use it to change files inside a Fortnite or UEFN install directory. **Verify is the sanctioned repair** for damaged or missing game files. Do not edit, delete, or replace files inside the Fortnite or UEFN install directory. That includes pak files, `Engine.ini`, and anything else under the game folder. Clearing the launcher **webcache** (below) is Epic's launcher-cache step. It is not a game-folder edit. ## Snapshot first The logs are on the workstation. This Worker cannot see them. From the uefn-mcp checkout, in Windows PowerShell: ``` powershell -NoProfile -File scripts/Get-EpicUpdateState.ps1 ``` Read the script comment header before you add a switch. The script is read-only: it prints launcher and install-helper state and does not install, verify, or delete. There is no hosted route for it. Do not add one. A missing click-Verify action would be a future **client** command on that same workstation, not a Worker tool. Trust the snapshot for which processes exist, which error strings are in the install-helper `UE-*.log`, and whether the main Fortnite install is Pending. Then take one signature below. Do not guess a signature the snapshot does not show. ## Signature A — launcher says it is still running The tile says Fortnite or UEFN is still running, so Update and Verify stay disabled, but the snapshot shows no Fortnite or UEFN process. 1. If the snapshot shows a real game or editor process, close that app. Then use the launcher system-tray **Exit**. Ending the window is not enough. 2. If the snapshot shows `EpicGamesLauncher`, `EpicWebHelper`, or `EpicOnlineServicesUserHelper` still alive after Exit, end those processes in Task Manager, then start the launcher once. 3. If the snapshot shows **none** of those processes and the UI still says the app is running, the lock is stale. A staged launcher self-update is the usual cause: the launcher has an update of its own waiting to apply, and the running-app flag survives the restart that never finished. Start the launcher again and let **its** update finish before you retry the game update. Epic's public help does not describe this false lock (gap). The symptom is reported on the Epic Developer Community (launcher shows Fortnite and UEFN still running after they were closed). Epic **does** document the launcher's own update failing for disk space: `SU-DS01`, `SU-DS02`, `SU-DL01`, and `SU-FC01` through `SU-FC05` mean the drive is full. Free space with Windows disk cleanup or by moving other data. Do not delete files inside the game install to make room. Then start the launcher again so the self-update can finish. `SU-PQR*` / `SU-PQE*` ("necessary prerequisites have failed") is a different launcher self-update failure. Epic's article says run the launcher as administrator, reinstall the Visual C++ redistributables, and confirm the install folder allows Read and Write. Follow that article. Do not apply it to a game-file verify failure. ## Signature B — IS-EO-ih_early_exit and BuildVerifyFail The tile retries and stops with `IS-EO-ih_early_exit`. The install-helper `UE-*.log` in the snapshot shows `BuildVerifyFail` with `BV02` or `BV05`. Epic has not published a help page for `IS-EO-ih_early_exit` (gap). Treat the early exit as the helper quitting. The verify code in that log is the cause. Repair that code. Do not edit `Engine.ini`. Community posts suggest download throttling, folder permissions, or an `Engine.ini` under the launcher config. Those posts disagree with each other, and none of them is Epic's published fix. Do not follow the ini edit. | Code in the log | Epic's published meaning | Next step | | --- | --- | --- | | BV02 / IS-BV02 | File missing or invalid | `chkdsk` on the install drive (Administrator Command Prompt, `chkdsk : /r /f`), then Windows Memory Diagnostic. Then **Verify**. | | BV03 / IS-BV03 | Install is corrupt | Confirm the volume is NTFS (This PC, drive Properties). Run Windows Memory Diagnostic. Epic also says try another drive. Then **Verify**. | | BV04 / IS-BV04 / IS-IN-BV04 | Build verification failed, hash mismatch | NTFS, Windows Memory Diagnostic, and install on the drive that has the compatible OS. Then **Verify**. | | BV05 on Fortnite or UEFN | Epic has no Fortnite article for this code (gap) | **Verify** Fortnite or UEFN. Do not use the Unreal Engine article below. | `IS-IN-BV05` on **Unreal Engine** is a different product. Epic's article says uncheck **Engine Source** on the engine install options. That step does not exist for Fortnite or UEFN. Do not tell a Fortnite or UEFN update to uncheck Engine Source. `chkdsk` and Windows Memory Diagnostic are the Windows tools Epic names on the BV02 and BV04 pages. They are not MCP tools. Verify is still required after they finish: Epic's verify article is the repair for files that do not match the manifest. ## Signature C — UEFN cannot move because Fortnite is Pending UEFN is a follower app. The launcher app id is `Fortnite_Studio`. It does not update while the main Fortnite install is **Pending** after an interrupted download. 1. Read the snapshot. If Fortnite is Pending, do not start with UEFN. 2. In the launcher, resume the Fortnite update. If resume is not offered, **Verify** Fortnite. 3. When Fortnite is no longer Pending, update or Verify UEFN. Do not delete `Manifests\*.item` files. Do not edit `LauncherInstalled.dat`. Community reports of `IS-0009` ("could not read installation information") start after those files were removed by hand, and Epic has no help page for `IS-0009` (gap). If the tile offers Library **Uninstall**, use that, then **Install**. If the tile stays on Update failed after Uninstall, stop. That record is Epic Support's, not a file edit. A queue that never starts, with no error and no Pending flag, is also thin in Epic's docs (gap). Exit from the tray, confirm the snapshot shows the helper processes gone, start the launcher, and resume. An Epic Developer Community thread (UEFN stuck on Queued) ended in Verify, then Uninstall and Install from the Library. Verify first. ## Other codes the tile can show Match the code in the snapshot. Then `search_verse_kb` `mode=docs` if you need the article text. - **IS-DS01** — not enough space before the install. Free space, or choose another volume with the launcher's Browse button on Install. - **IS-DS02** — ran out of space during the install. Same as DS01. Epic also lets you drop optional Fortnite features: Library, three dots, Options, uncheck what you do not need, Apply. That is a launcher control. It is not a hand edit of the install. - **IS-MF02-5, IS-MF03-5, IS-MF02-32, IS-MF02-225** — BattlEye or Easy Anti-Cheat did not start. This is a **launch** failure after files are present, not a BuildVerifyFail. Epic says set those two services to Automatic (Delayed Start), then clear the launcher webcache, then run the launcher as administrator. - **LS-0006** and **IS-INFO-DSTCVPAT** — the launcher cannot install or update. Epic's order: run the launcher as administrator, clear the launcher webcache, Library Uninstall, then Install. Epic's last resort is to Exit the launcher and delete the **whole** game folder (default `C:\Program Files\Epic Games\`), then Install again. That is an uninstall, not an edit of files inside the folder. If Verify is available, run Verify before that last resort. - **Launcher webcache** — Epic's cache clear, used when a download size looks wrong and by the LS-0006 / MF articles. After tray Exit, under `%localappdata%\EpicGamesLauncher\Saved\`, delete only `webcache`, `webcache_4147`, and `webcache_4430` (whichever exist). Start the launcher. Do not delete the game directory in this step. ## Verify Epic's verify article: 1. Open the Epic Games Launcher. 2. Find the game in the Library. 3. Click the three dots on that row. 4. Select Manage. 5. Click Verify. 6. Wait until validation finishes. Saved data is not part of this repair. Run it on Fortnite and on UEFN separately when both failed. Verify stays disabled while signature A is still true. Clear that lock first. No hosted tool clicks Verify. Do not invent `verify_game` on this Worker. If a client tool is added later whose description says it starts this same Library Verify, call that tool. Until then the person at the machine clicks Verify. ## EXAMPLE — v42.30 rollout EXAMPLE only. Not a rule that these failures belong to one version. During the v42.30 rollout the same three signatures showed up together. The launcher said Fortnite and UEFN were still running while no game process existed (a staged launcher self-update). The install helper retried `IS-EO-ih_early_exit` because `UE-*.log` contained `BuildVerifyFail` BV02 or BV05. UEFN (`Fortnite_Studio`) could not update because the main Fortnite install was Pending after an interruption. Later versions can show any one of those signatures on its own. Diagnose from the snapshot, not from the version number. ## Sources Epic help (primary): - Verify: `https://www.epicgames.com/help/c-202300000001619/c-5719341627163/a202300000017217?lang=en-US` - IS-BV02: `https://www.epicgames.com/help/en-US/c-Category_EpicGamesStore/c-EpicGamesStore_ErrorCodes/is-bv02-file-missing-or-invalid-a000084896` - IS-BV03: `https://www.epicgames.com/help/en-US/c-Category_EpicGamesStore/c-EpicGamesStore_ErrorCodes/is-bv03-install-failed-the-installation-is-corrupt-a000085707` - IS-BV04 / IS-IN-BV04: `https://www.epicgames.com/help/en-US/c-Category_EpicGamesStore/c-EpicGamesStore_ErrorCodes/is-bv04-or-is-in-bv04-build-verification-failed-due-to-mismatched-hash-a000084878` - IS-IN-BV05 (Unreal Engine Engine Source only): `https://www.epicgames.com/help/en-US/epic-games-store-c-202300000001639/error-messages-c-202300000001736/i-encountered-error-code-is-in-bv05-when-trying-to-install-unreal-engine-a202300000013584` - IS-DS01: `https://www.epicgames.com/help/c-202300000001639/c-202300000001736/is-ds01-out-of-disc-space-before-trying-to-install-a-game-a202300000015357` - IS-DS02: `https://www.epicgames.com/help/en-US/c-Category_EpicGamesStore/c-EpicGamesStore_ErrorCodes/is-ds02-ran-out-of-disc-space-during-installation-a000084873` - SU-DL01 / SU-DS01 / SU-DS02 / SU-FC0*: `https://www.epicgames.com/help/en-US/c-Category_EpicGamesStore/c-EpicGamesStore_ErrorCodes/su-dl01-su-ds01-su-ds02-su-fc01-su-fc02-su-fc03-su-fc04-or-su-fc05-error-a000087217` - IS-MF02 / IS-MF03: `https://www.epicgames.com/help/en-US/c-Category_EpicGamesStore/c-EpicGamesStore_ErrorCodes/is-mf02-5-is-mf03-5-in-fortnite-is-mf02-32-or-is-mf02-225error-a000087214` - LS-0006: `https://www.epicgames.com/help/en-US/c-Category_EpicGamesStore/c-EpicGamesStore_ErrorCodes/ls-0006-installation-failed-a000084968` - IS-INFO-DSTCVPAT: `https://www.epicgames.com/help/en-US/c-Category_EpicGamesStore/c-EpicGamesStore_ErrorCodes/is-info-dstcvpat-error-appears-when-trying-to-update-a-game-a000085705` - Misreported download size, Verify, and webcache: `https://www.epicgames.com/help/en-US/c-Category_EpicGamesStore/c-EpicGamesStore_LauncherSupport/why-do-download-file-sizes-seem-larger-than-normal-especially-after-an-update-in-epic-games-launcher-a000086940` Docs gaps, where community agrees on the symptom and Epic is silent on the mechanism: - False "still running" after close: `https://forums.unrealengine.com/t/epic-games-launcher-glitch/2724046` - UEFN stuck Queued: `https://forums.unrealengine.com/t/uefn-update-queue-stuck/2625428` - IS-0009 after manifest edits (do not repeat those edits): `https://forums.unrealengine.com/t/unable-to-resolve-uefn-is-0009-update-failed/2642718` - `IS-EO-ih_early_exit` community thread (do not follow the ini edit): `https://www.reddit.com/r/FortNiteBR/comments/1uh99uy/error_code_iseoih_early_exit/` No Epic YouTube video was found that contradicts the help articles above. An X search on 2026-10-06 for `IS-EO-ih_early_exit` and `Fortnite_Studio` returned no posts. Prefer the help articles when a community post disagrees.